Sauté the onion slices with garlic and thyme in a pan for 5 minutes.
You can either use a mandolin to cut the potato thin (watch your fingers!) or a knife to do it.
After this, Place the potato slices on a baking sheet lined with baking paper. Continue this process until your tray is full. Then, fill it with chicken stock. Bake at 180°C for 30 minutes. Bake for 30 minutes at 180C.